Scattering and Doppler spectral analysis for a flying target above a 3-D sea surface

Aiming to find the Doppler spectra of a flying target at low altitude above a sea surface, an iterative hybrid method is employed to solve this complex composite 3-dimensional (3-D) electromagnetic scattering problem. This method calculates electromagnetic (EM) scatterings of the target and the sea surface separately, and then the mutual EM coupling effects are added through an iterative process. The Doppler spectra from the target flying at different velocities are analyzed by using quasi-stationary algorithm at different incident angles. The influence on the Doppler spectral broadening which is induced by the EM coupling effects is analyzed as well.